How to troubleshoot slow internet speeds

MarkTrammell copy

I don’t need to tell you that the experience of dealing with a slow internet connection is a frustrating one. Almost everyone who has internet has experienced at some stage or another, pages loading slowly or not at all, files taking forever to download, missing clumps of hair on your head.

Internet is a complex thing – routers, cables, backbones, modems – I could list hundreds of components. This unfortunately means there are many things that could potentially cause problems.

Most of the time things run very smoothly, but when something does go wrong it needs to be isolated and dealt with. The problems can come from your Internet Service Provider (ISP) the exchange, or the copper beneath the street. But sometimes the root of the problem is inside your own home. In fact, most of the calls we get about slow internet speeds are resolved before we have to get technicians involved! 

Why bother?

More often than not the problem is within your direct sphere of influence. Sometimes we will need to be notified and a technician will need to fix something, but we will always ask you to run through some troubleshooting steps before doing so, I’m sure you don’t want to have to wait for a technician to visit, only to find that something was not plugged in or configured incorrectly.

Inward journey, look within your house

The most important step is figuring out what is causing the problem! Slow speeds can manifest in 2 ways which means the way you go about troubleshooting and fixing can be quite different.

The first way is a low “sync” speed, this means there is a physical degradation or issue somewhere that is interfering with the ADSL signal on the phone line.

  • You can check for low sync speed by logging into your modem, going to the “Status” page and checking your “Downstream” Or “Data Rate” – the wording varies depending on your modem manufacturer.

The second way is slow “data flow”, this means your physical connection to the internet is fine, but something is slowing down the transfer of data, such as a program or user basically “hogging” the connection. Think of it as someone eating all the cake and leaving you with crumbs.

  • You can use an independent site to check this, such as or you can download the “adsl.test” file from our FTP: and multiplying the speed you download it at by 10 – this will give you a rough idea of your current speed so you can compare it to the sync speed in your modem, if there is much of a difference then you have a data-flow problem.

First steps

Here is a list of steps to run through to figure out where the problem is. If you notice an improvement on any step, start putting things back to the way they were, one by one and checking the speed each time. If the speed drops, you have found the cause.

  • Pick up the phone. But not to make a call! Listen for any noise or static on your phone line. Your ADSL service runs through the phone line so any interference on it can greatly affect internet quality (Not applicable on Naked DSL). Here is a guide for troubleshooting phone issues:
  • Wi-Fi versus Ethernet. If you are using Wi-Fi with your modem, check if you are having the same problem when you plug a device in with an Ethernet cable – you could have a weak Wi-Fi signal, or something could be interfering. Test your speed (as mentioned earlier) when using both.
  • Check for viruses or spyware. These are ever-present threats to your digital life and can make life very difficult if unchecked! At the same time, some virus/spyware software can also hinder your internet speeds – you will need to check with software makers or google and see if anyone else is having issues with it and what they have done.
  • Congestion. Too many cars on the road, or: your kids/siblings/parents/room-mates are downloading the entire internet and not being completely honest about it – as someone who worked in support for several years, this happens much more often than you would think.
  • Network congestion. This is pretty rare but some areas may have too many people connected to the same equipment, check your speeds during off-peak times to see if it is any better. Peak usage times are usually after work until bedtime, so usually 5pm – 10pm.

Next steps

If none of the above steps help you, you will need to troubleshoot further – this may involve getting physical so roll up your sleeves! Again, if you notice an improvement, start retracing your steps until the speed drops.

  • Isolation test: Unplug any device that uses a phone socket, handsets, filters, adapters, faxes, pay TV and plug in 1 standard phone handset (if available) and listen for line noise/static again. If it is clear, plug your modem in instead (leave everything else out as well, including the filter) and check your speed.  (This step is not applicable if you have Naked DSL.)
  • More Isolation: With the modem plugged in by itself, turn off or disconnect any other computers or devices that may be using the connection and see if there is any difference.
  • Test different cables. Try another Ethernet cable and phone cable (from the modem to the phone socket) and even test another phone socket if your house has more than one.
  • Test another modem if possible. This step is always left last as not many people have access to more than one modem.

If you have tried everything listed and still cannot find the cause of the problem, or if you need help with any of the steps, you can contact our friendly support team on 13 22 58 or email us at for further assistance.

If you think that your home set up is quite complicated and needs some attention – you can always arrange for a techii to come out and visit you. Our techii team are staffed by a group of experienced friendly people who will take a look at issues that you might not even have considered. Our previous article – Techii to the rescue – gives you a good idea of how they can help.

Getting a head start on some initial troubleshooting before contacting a support team member can save you some time, and it might even fix the problem without having to call!  Customers should always feel free to tell our representatives what they have already tried, you might even like to use this blog as a checklist.  We’re always happy to help though, so if you’re a little wary of tinkering around yourself, or if problems persist, you can contact our friendly support team on 13 22 58 or email us at for further assistance.

Photo credit: Mark Trammell


  1. Paul says:

    One thing you didn’t mention is alarms are often using the same line (and usually overlooked) they need to have a filter as well. A central filter will isolate the modem to it’s own line and negate the use of use of filters on all the telephone lines. Needs a sparky to install though.

  2. Kenneth Williams says:

    I find it very reassuring to receive this kind of advice because it assumes very little knowledge on my part.Thank you.

    • E. Venables says:

      @Kenneth Williams, Likewise, Kenneth

    • Ben says:

      I found comparing modem “downstream” with speed test results very useful. My modem downstream rate is in bps (1536000) but the speed test results are in mbps (1.3) – but it’s easy to use google to convert (1 536 000 (bits per second) = 1.46484375 Mbps). This showed that I had good data flow, but my poor old modem is doing the best job it can. Time for me to upgrade to a faster modem.

  3. Phil C says:

    A very good guide but I believe 2 key first steps were missed. 1) Reboot the computer and 2) Power cycle the modem / router. If neither have been restarted in a long time a simple restart fixes so many problems.

  4. Adrian says:

    The first thing I do is turn my modem off, and turn it back on again. This usually solves the problem.

    I said in an Irish accent.

  5. Brian Simpson says:

    Well written & informative for an amateur internet user !, I will print this off for future reference .

  6. Pommie says:

    “You can check for low sync speed by logging into your modem, going to the “Status” page and checking your “Downstream” Or “Data Rate”

    Thanks. But you don’t tell us what a low sync speed is.

  7. Chris grainger says:

    If I use , speed test, what numbers shoul I expect to get?

    • Christian Polson-Brown says:

      Hi Chris,

      The speeds you can expect depend on a couple of factors, mainly the type of service you have with us (ADSL1/2/2+) and the physical infrastructure you’re connecting to (quality of line, distance from exchange).

      As a general rule we consider anything below 1.5Mbps (1500Kbps) a faulty service, but best to give our support team a call on 13 22 58 if you have more questions or concerns.


  8. Steve says:

    Nothing much helps when you’re 5Km or so from the nearest exchange.

  9. Sandi says:

    Reading this I’m still confused. The article talks about ADSL and DSL and checking phone lines, but what about NBN? I don’t have a phone line and still have slow internet speeds, particularly in the morning.

    • Christian Polson-Brown says:

      Hi Sandi,

      Sorry about the confusion, this article does relate specifically to customers using our ADSL services. Troubleshooting NBN speeds is a little different, you can read our iiHelp page with some suggestions here, and call our support team on 13 22 58 if you’d like a hand.


  10. Glenys Brady says:

    What if it still goes on after 5 months and your ISP still can’t figure it out??????

  11. Reg Pollock says:

    Thank you for your continuing support for your clients.

    Your messages are received with gratitude and your assistance has been and is valued.

    I can recall the days when the personal visits of support were made.

    Best wishes
    Reg Pollock

  12. Al Bondinga says:

    when my internet speed slows to dial-up it has nearly always been corroded pins in the phone connectors on the phone modem splitter/filter – check the pin connectors – if you see green corrosion replace splitter/filter

  13. Robbie White says:

    Another point to consider is the age of your modem. Any modem over three years old is out of date, much like computers and mobile phones. If you want speed, and I am not in any way disputing the wisdom and expertise of Karl Adam, get yourself a new modem, and get an expert to set it up.

  14. Gerald Eaton says:

    I found the Bob lite modem router when configured as an NBN router only is just not suitable” PS3 and a TV would not connect swapped the Bob with a cheap and small D-Link 600 L router I had spare now every thing is running just fine.

  15. Adrian Adams says:

    Your Trouble shooting sites are rubbish — and invite 2nd hand operators to “fix” my computer. BAD MOVE. BAD PUBLIC RELATIONS.

  16. Maruf says:

    It all sounds good in theory but it would have better if iiNet did what the auther said. I have NBN connection at home where I get 7-8 Mbps while I am paying for 100 Mbps speed. Surely iiNet don’t have any techi in ACT who can fix this even though I have done all the troubleshooting as advised. Poor service than it’s lucrative advertises by iiNet.

  17. Humphrey Hayes says:

    Thankyou for above,very informative.
    What is “naked dsl”?

    • Christian Polson-Brown says:

      Hi Humphrey,

      Naked DSL is an internet service where we have removed the landline phone service, which is still a requirement of other ADSL services. Naked DSL means you no longer have to pay line rental for a traditional phone service if you don’t want one, and we supply a free VoIP (voice over internet) service with the Naked DSL.

      More info here


  18. Regina says:

    I’m sure this information relates to customers on fibre but is it the same? If not, what steps can fibre customers take? I’m on the South Brisbane exchange.

    I’m a PC pygmy so I too appreciate this advice and information – the simpler and less techii terms the better. Thanks.

    • Amy Pearce says:

      Hi Regina,

      The South Brisbane fibre services are supplied a little differently, for any troubleshooting, we’d suggest giving us a call (132258) to help out.
      Worst case scenario is we lodge a fault for a technician to come out and take a look at the hardware running up to you house.

      – Amy

  19. You forgot to mention: Telstra might steal your landline and no one will tell you it has happened, until you find that things are not working as they should.

  20. Vic says:

    How do I log into my modem?

    • Amy Pearce says:

      By going to your internet browser (Internet Explorer, Firefox, Chrome etc.) and typing in and hitting enter.
      Once there, you will need to enter in your modem username and password. If it is an iiNet supplied modem, it would likely be admin/password.
      You are now in your modem configuration page!

      If you need any further help, please call our friendly Support Team on 13 22 58.

      – Amy

  21. Phil G. says:

    One more STEP should be added. I call it HOGGING where the likes of MICROSOFT are doing ‘Updates’ automatically. When my computer grinds to a halt, the 1st thing I do is check the ADSL2+ router and sure enough, the router lights are going flat out. Finally, when the updates are complete, life returns to normal. So, no need to run around the house doing other checks. No commentator in magazines or on talk back radio shows ‘never’ mention this possibility. They always suspect the equipment with long winded discussions. (appreciate iiNets thoughts on this)

  22. Helen says:

    Being well over 70 the information could be in heirogylyphics its a foreign language, so probably stuck with it, wonderful